Unexpected Floating Point Precision Issue When Multiplying by 100

[jigexiansen]

I encountered an unexpected behavior when converting a string to a float64 and then performing a multiplication operation. The result seems to have a precision issue.

Steps to Reproduce:

1. Use the following code snippet:

   package main
   
   import (
       "fmt"
       "github.com/spf13/cast"
   )
   
   func main() {
       strValue := "19.9"
       floatValue := cast.ToFloat64(strValue) // 19.9
       fmt.Println(floatValue)                // 19.9
       fmt.Println(floatValue * 100)          // 1989.9999999999998
   }

2. Run the code.

Expected Behavior:

The output should be:

19.9
1990

Actual Behavior:

The output is:

19.9
1989.9999999999998

Additional Context:

• Go version: go1.22.5
• Operating System: Darwin 23.5.0 arm64
• github.com/spf13/cast version: v1.7.0

It seems like there is a floating point precision issue when multiplying the float64 value by 100. Is this the expected behavior due to the nature of floating point arithmetic in Go, or is there a way to handle this more accurately?

Thank you for your assistance!

[Baxromumarov]

This issue is not related to this cast package. It is golang float64 case. You can try it
`
package main

import (
"fmt"
)

func main() {
var floatValue float32 = 19.9
fmt.Println(floatValue * 100) // 1989.9999999999998
}
`